Re: Why not build kernel with -O3

[Pengfei Yuan]

2015-04-08 20:19 GMT+08:00 Richard Weinberger <richard.weinberger@xxxxxxxxx>:
> On Wed, Apr 8, 2015 at 3:00 AM, Pengfei Yuan <0xcoolypf@xxxxxxxxx> wrote:
>> Could you please provide some examples that I can investigate?
>> Thanks!
>
> It would be awesome if you could find out which gcc optimizations
> cause the speed up.
> "gcc -c -Q -O3 --help=optimizers" will help you.
>

This is really helpful.
But I can only find very short description for each option from
https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html

> Please also double check your results.
> You need do to multiple runs, etc...
> Especially the redis speed up looks odd. Does redis really spend that much time
> in the kernel?

Redis is special among the six applications because it is single-threaded.

Yuan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/